.\"
.\" Copyright (c) 2001-2005
.\"	Fraunhofer Institute for Open Communication Systems (FhG Fokus).
.\"	All rights reserved.
.\" Copyright (c) 2006,2018
.\"	Hartmut Brandt
.\"	All rights reserved.
.\"
.\" Author: Harti Brandt <harti@FreeBSD.org>
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" $Begemot: gensnmptree.1 383 2006-05-30 07:40:49Z brandt_h $
.\"
.Dd April 2, 2019
.Dt GENSNMPTREE 1
.Os
.Sh NAME
.Nm gensnmptree
.Nd "generate C and header files from a MIB description file"
.Sh SYNOPSIS
.Nm
.Op Fl dEeFfhlt
.Op Fl I Ar directory
.Op Fl i Ar infile
.Op Fl p Ar prefix
.Op Ar name Ar ...
.Sh DESCRIPTION
The
.Nm
utility is used to either generate C language tables and header files from
a MIB description or to numeric OIDs from MIB descriptions.
The first form is used only for maintaining the
.Xr bsnmpd 1
daemon or for module writers.
The second form may be used by SNMP client program writers.
.Pp
If none of the options
.Fl e ,
.Fl E
or
.Fl t
are used
.Nm
reads a MIB description from its standard input and creates two files: a
C-file
.Ar prefix Ns tree.c
containing a table used by
.Xr bsnmpd 1
during PDU processing
and a header file
.Ar prefix Ns tree.h
containing appropriate declarations of the callback functions used in this
table, the table itself and definitions for all enums.
.Pp
The following options are available:
.Bl -tag -width ".Fl E"
.It Fl d
Switch on debugging.
.It Fl E
Extract enumerations and bit constructs.
In this mode the tool emits
a header file that contains for each type given on the command line a
C-enum definition and a preprocessor define that may be used to map
values to strings.
.It Fl e
.Nm
expects MIB variable names (only the last component) on its command line.
It reads a MIB specification from standard input and for each MIB variable
name emits three C preprocessor defines on its standard output:
.Bl -tag -width ".Va OIDLEN_ Ns Ar Name"
.It Va OIDX_ Ns Ar name
This define can be used to initialize a
.Va struct asn_oid
in the following way:
.Pp
.Dl const struct asn_oid oid_sysDescr = OIDX_sysDescr;
.It Va OIDLEN_ Ns Ar name
is the length of the OID.
.It Va OID_ Ns Ar name
is the last component of the OID.
.El
.It Fl F
emit definitions for C-functions includeable in a C-file that do some basic
stuff on enums like value checking and conversion between value and strings.
.It Fl f
emit definitions for inline C-functions that do some basic
stuff on enums like value checking and conversion between value and strings.
.It Fl h
Print a short help page.
.It Fl I Ar directory
Add the named directory to the include path just before the standard include
directories.
.It Fl i Ar infile
Read from the named file instead of standard input.
.It Fl l
Generate local preprocessor includes.
This is used for bootstrapping
.Xr bsnmpd 1 .
.It Fl t
Instead of normal output print the resulting tree.
.It Fl p Ar prefix
Prefix the file names and the table name with
.Ar prefix .
.El
.Sh MIBS
The syntax of the MIB description file can formally be specified as follows:
.Bd -unfilled -offset indent
 file := top | top file

 top := tree | typedef | include

 tree := head elements ')'

 entry := head ':' index STRING elements ')'

 leaf := head type STRING ACCESS ')'

 column := head type ACCESS ')'

 type := BASETYPE | BASETYPE '|' subtype | enum | bits

 subtype := STRING

 enum := ENUM '(' value ')'

 bits := BITS '(' value ')'

 value := INT STRING | INT STRING value

 head := '(' INT STRING

 elements := EMPTY | elements element

 element := tree | leaf | column

 index := type | index type

 typedef := 'typedef' STRING type

 include := 'include' filespec

 filespec := '"' STRING '"' | '<' STRING '>'
.Ed
.Pp
.Ar BASETYPE
specifies a SNMP data type and may be one of
.Bl -bullet -offset indent -compact
.It
NULL
.It
INTEGER
.It
INTEGER32 (same as INTEGER)
.It
UNSIGNED32 (same as GAUGE)
.It
OCTETSTRING
.It
IPADDRESS
.It
OID
.It
TIMETICKS
.It
COUNTER
.It
GAUGE
.It
COUNTER64
.El
.Pp
.Ar ACCESS
specifies the accessibility of the MIB variable (which operation can be
performed) and is one of
.Bl -bullet -offset indent -compact
.It
GET
.It
SET
.El
.Pp
.Ar INT
is a decimal integer and
.Ar STRING
is any string starting with a letter or underscore and consisting of
letters, digits, underscores and minuses, that is not one of the keywords.
.Pp
The
.Ar typedef
directive associates a type with a single name.
.Pp
The
.Ar include
directive is replaced by the contents of the named file.
.Sh EXAMPLES
The following MIB description describes the system group:
.Bd -literal -offset indent
include "tc.def"

typedef AdminStatus ENUM (
	1 up
	2 down
)

(1 internet
  (2 mgmt
    (1 mib-2
      (1 system
        (1 sysDescr OCTETSTRING op_system_group GET)
        (2 sysObjectId OID op_system_group GET)
        (3 sysUpTime TIMETICKS op_system_group GET)
        (4 sysContact OCTETSTRING op_system_group GET SET)
        (5 sysName OCTETSTRING op_system_group GET SET)
        (6 sysLocation OCTETSTRING op_system_group GET SET)
        (7 sysServices INTEGER op_system_group GET)
        (8 sysORLastChange TIMETICKS op_system_group GET)
        (9 sysORTable
          (1 sysOREntry : INTEGER op_or_table
            (1 sysORIndex INTEGER)
            (2 sysORID OID GET)
            (3 sysORDescr OCTETSTRING GET)
            (4 sysORUpTime TIMETICKS GET)
        ))
      )
    )
  )
)
.Ed
.Sh SEE ALSO
.Xr bsnmpd 1
.Sh AUTHORS
.An Hartmut Brandt Aq harti@FreeBSD.org
